From 8115f3274eab06743603aec502ae311e3bf0724b Mon Sep 17 00:00:00 2001
From: LinkTed <link.ted@mailbox.org>
Date: Mon, 3 Jan 2022 20:30:46 +0200
Subject: linux: Add support for No New Privs flag

This add No New Privs flag for start-stop-daemon and supervise-daemon
by adding --no-new-privs flag. As a result, the user set the No New
Privs flag for the program should run with.
see PR_SET_NO_NEW_PRIVS prctl(2)
---
 src/rc/supervise-daemon.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

(limited to 'src/rc/supervise-daemon.c')

diff --git a/src/rc/supervise-daemon.c b/src/rc/supervise-daemon.c
index 5c5c01fc..85d5efbb 100644
--- a/src/rc/supervise-daemon.c
+++ b/src/rc/supervise-daemon.c
@@ -32,6 +32,7 @@
 
 #ifdef __linux__
 #include <sys/syscall.h> /* For io priority */
+#include <sys/prctl.h> /* For prctl */
 #endif
 
 #include <ctype.h>
@@ -79,6 +80,7 @@ const struct option longopts[] = {
 	{ "healthcheck-delay",        1, NULL, 'A'},
 	{ "capabilities", 1, NULL, 0x100},
 	{ "secbits", 1, NULL, 0x101},
+	{ "no-new-privs", 0, NULL, 0x102},
 	{ "respawn-delay",        1, NULL, 'D'},
 	{ "chdir",        1, NULL, 'd'},
 	{ "env",          1, NULL, 'e'},
@@ -106,6 +108,7 @@ const char * const longopts_help[] = {
 	"set a health check timer",
 	"Set the inheritable, ambient and bounding capabilities",
 	"Set the security-bits for the program",
+	"Set the No New Privs flag for the program",
 	"Set a respawn delay",
 	"Change the PWD",
 	"Set an environment string",
@@ -164,6 +167,9 @@ static bool verbose = false;
 static cap_iab_t cap_iab = NULL;
 static unsigned secbits = 0;
 #endif
+#ifdef PR_SET_NO_NEW_PRIVS
+static bool no_new_privs = false;
+#endif
 
 extern char **environ;
 
@@ -437,6 +443,13 @@ static void child_process(char *exec, char **argv)
 	}
 #endif
 
+#ifdef PR_SET_NO_NEW_PRIVS
+	if (no_new_privs) {
+		if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) == -1)
+			eerrorx("Could not set No New Privs flag: %s", strerror(errno));
+	}
+#endif
+
 	/* remove the controlling tty */
 #ifdef TIOCNOTTY
 	ioctl(tty_fd, TIOCNOTTY, 0);
@@ -854,6 +867,14 @@ int main(int argc, char **argv)
 #endif
 			break;
 
+		case 0x102:
+#ifdef PR_SET_NO_NEW_PRIVS
+			no_new_privs = true;
+#else
+			eerrorx("The No New Privs flag is only supported by Linux (since 3.5)");
+#endif
+			break;
+
 		case 'D':  /* --respawn-delay time */
 			n = sscanf(optarg, "%d", &respawn_delay);
 			if (n	!= 1 || respawn_delay < 1)
-- 
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